For removing coarser and finer impurities and particles of soil from these suspensions which are used in the paper and pulp industry, more precisely, aqueous suspensions of fibrous pulp, hydrocyclones are used almost exclusively, and have proved particularly suitable for this purpose due to their basically simple construction and the lack of moving parts in most cases. However, the throughflow of fibre suspension in a normal pulp or paper factory is enormous, and for this reason a very great number of these hydrocyclones are necessary to provide an adequate level of cleaning capacity. This gives rise to a whole series of practical problems, for which various solutions have been suggested over the course of the years.
These practical problems can be said basically to be three. Firstly, the great number of cyclones take up a great amount of space if they are lined up in parallel-connected groups, in the most obvious way. Various ways of "packaging" the cyclones have been proposed to solve this problem of space; the best known of these (see, for example, Swedish Pat. No. 200 549) is based on the cyclones being positioned in circular horizontal layers or groups in which they are disposed symmetrically, radially orientated with their tapered ends directed inwards towards a common centre. These layers or assemblies are then piled up on top of each other to the required height, thus providing a compact and space-saving system. However, this does not provide a good solution for the two remaining problems, one of which concerns the monitoring of the operation of the individual cyclones in an assembly. It is known for breakdowns in operation to occur readily in the form of clogging, blockages and the like at the narrow outflow ends of the cyclones where the separated portion of the suspension, containing particles of soil and known as the reject, flows out. It is highly desirable for it to be possible to monitor the flow behaviour at these narrow points visually, since disturbances in the flow are most frequently very clearly visible just here.
The third and by no means least important problem concerns ease of mounting, that is to say, how easy or difficult it is to mount and dismount the individual cyclones in an assembly. A very important object is in fact that each individual cyclone in an assembly should be both readily accessible from the outside and easy to dismount and mount, without other parts of the assembly having to be taken out, to allow intervention or adjustment.
As far as the fibre suspension cleaning plant based on cyclone assemblies which is in use in pulp factories throughout the world is concerned, it cannot be said that a satisfactory solution has been found for these practical constructional problems.
The object of the invention is therefore to provide as comprehensive as possible a solution to these problems, and this object is achieved in that a cyclone package of the type described in the preamble to patent claim 1 is designed according to the invention in the manner indicated in the characterising part of the claim.